Various substrates or various substrates having treated surface layers are used in various fields, and adverse effects brought about by water to the surface of such substrates are problematic.
For example, in transportation equipments such as electric cars, automobiles, ships or aircrafts, the surface of an exterior part such as an outer panel, a window glass, a mirror or a display surface material, an interior part such as an instrument panel, or other articles, is desired to be always clean. If rain drops, dusts or soils become attached, or moisture is condensed due to the temperature or humidity in the air, on the surface of an article in a transportation equipment, the outer appearance will be impaired. If such is a surface which is directly visually observed or a surface which is directly touched by a person, it may give an unpleasant feeling or may create a hygienic problem. Further, such may bring about a deterioration of the inherent function which the article for a transportation instrument has. Especially in a case where the article for the transportation equipment is an article for which transparency or see-through property is required (such as a window glass or a mirror), a deterioration of the transparency or see-through property may mean that the purpose intended by the article can not be attained, and may cause a serious accident.
A means to remove water drops (such as removal by wiping off or by means of a wiper) may sometimes impart fine scratch marks on the surface. Further, such scratch marks may sometimes be widened by foreign particles accompanying water drops. Furthermore, it is well known that when moisture is attached to a glass surface, glass components are likely to elute into the moisture, whereby the surface will be eroded, thus leading to so-called scorching. If the surface is strongly polished or abraded to remove this scorching, a fine roughness is likely to form. At the see-through portion made of glass having substantial scorching or a fine roughness on its surface, its basic function is lowered, and scattering of light on its surface is substantial, whereby it tends to be difficult to secure the field of view, and consequently there will be a problem in securing the safety.
Further, moisture is likely to hazardously influence the surface of an article for a transportation instrument and to promote damage, soiling, yellowing or corrosion. Otherwise, it may induce a change in the electrical characteristics, the mechanical properties or the optical properties of the article for a transportation equipment. The adverse effects of this type brought by water are problematic not only in the field of articles for transportation equipments but also in various fields including articles for building or building decoration or articles for electric or electronic equipments.
Under these circumstances, it is desired to impart to the substrate surface a characteristic such that water drops scarcely attach to the substrate surface or attached water drops can easily be removed (such a characteristic will hereinafter be referred to simply as a water drop removal property). Heretofore, to impart a water drop removal property to a surface, surface treating agents for direct application, such as a surfactant and a silicone oil made of silicone wax or organo polysiloxane, have been proposed.
However, such surface treating agents require pretreatment for application in many cases, and have a problem that nonuniformity in application is likely to occur. Further, the adhesive properties of such treating agents to the substrates are rather poor, whereby the durability of the water drop removal property has been inadequate, and the application range has been rather limited.
When the influence of moisture is taken into consideration, it is necessary to establish a measure not only for various substrates to be produced the future but also for various substrates already being used. In this case, it is necessary to impart the water drop removal property simply by direct application to various substrates at normal temperatures. For example, when a case is taken into account wherein such treatment is to be applied to an automobile front glass already being used, it is not economical to replace the front glass of every automobile, or it is not practical to conduct baking after the application. Also from such an aspect, it is practically difficult to solve the problems by the conventional treating agents.
The present invention has been accomplished in view of the above problems. Namely, during the course of the research and study for a treating agent which is capable of solving the drawbacks inherent to the conventional treating agents, the present inventors have found a treating agent which is applicable to various types of substrates and which exhibits an excellent water drop removal property, and have confirmed that various substrates treated by such a treating agent are suitable for use as substrates having a water drop removal property, particularly for transportation equipments or for building and building decoration. The present invention has been completed on the basis of these discoveries.